Turbine having variable-angle nozzle guide vanes

ABSTRACT

A turbine being a ring of variable-angle nozzle guide vanes each having a driving pinion engaging an annular rack movable circumferentially to effect simultaneous turning of the vanes, the rack being connected to an actuating member by a leaf spring flexible in a direction toward and away from the circumference of the annular rack, thereby to avoid a pivotal joint between the actuating member and the rack in a very hot region of the turbine.

United States Patet [56] References Cited UNITED STATES PATENTS 3/1938 Seelig....

[72] lnventor Mark Cary Sedgwick Barnard Solihull, England [21] Appl. No. 851,703

[22] Filed Aug. 20, 1969 [45] Patented Apr. 13, 1971 [73] Assignee Leyland Gas Turbines Limited Solihull, England [32] Priority Sept. 17,1968

FOREIGN PATENTS 544,440 4/1942 GreatBritain................

Great Britain 44120/68 415/160 813,343 5/1959 Great Britain................ 415/160 Primary Examiner-Henry F. Raduazo Att0rneyMawhinney & Mawhinney ABSTRACT: A turbine being a ring of variable-angle nozzle [54] TURBINE HAVING VARIABLE-ANGLE NOZZLE guide vanes each having a driving pinion engaging an annular GUIDE VANES rack movable circumferentially to effect simultaneous turning of the vanes, the rack being connected to an actuating member by a leaf spring flexible in a direction toward and 4 Claims, 1 Drawing Fig.

415/160 F0ld 17/00 away from the circumference of the annular rack, thereby to [50] Field 415/160, avoid a pivotal joint between the actuating member and the 161, 162, 163 rack in a very hot region of the turbine.

51 im. c|...........

PATENTEUAPR] 3:97: 35,74,473

INv ram MARK CAaY enema: BARNARD A-r-ro 2 N EY TURBINE HAVING VARIABLE-ANGLE NOZZLE GUIDE VANES The invention relates to a turbine having a ring of variableangle nozzle guide vanes.

In one arrangement proposed hitherto, each nozzle guide vane is arranged to be turned about an axis extending longitudinally thereof by a pinion engaging an annular rack coaxial with the turbine and arrangement to be reciprocated by bellcrank lever means actuated by a fluid-operated plunger, One such arrangement proposed hitherto includes a connecting link pivotally attached at one end thereof to a bellcrank lever and at the other end thereof to the rack. This suffers from the disadvantage that as the link is pivotally attached at each end thereof, there could be wear at each pivot, resulting in angular movement of the bellcrank lever being incorrectly transmitted to the rack and hence to the vanes and also from the disadvantage that there are relatively sliding surfaces at the pivots, particularly at the pivot adjacent the rack, which is in a very hot region of the turbine.

According to the invention, a turbine having a ring of variable-angle nozzle guide vanes, each arranged to be turned simultaneously about an axis extending longitudinally thereof by one of a plurality of pinions engaging an annular rack coaxial with the turbine, includes a substantially tangentially extending leaf spring secured at one end thereof to the annular rack end at the other end thereof to a lever by which the annular rack is to be angularly turned to effect simultaneous turning of the pinions and hence of the nozzle guide vanes, the leaf spring being flexible in a direction toward and away from the circumference of the annular rack.

The leaf spring may either be mounted directly on the lever or be attached to a link pivotally connected at the end thereof remote from the leaf spring to the lever.

The lever may be one arm of a bellcrank lever having another arm arranged to be moved by operating means, for example a fluid-operated plunger.

By employing a leaf spring to transmit actuating movement to the rack relatively sliding surfaces on the spring or a mounting therefor and on the annulus are avoided and therefore there is no possibility of seizure or wear problems at high temperature, as there would be by employing a conventional pivot joint. Furthermore, the leaf spring can flex as a result of angular movement of the lever or the connecting link, where the latter is provided, and the lever or the link is always aligned with the adjacent portion of the leaf spring.

By way of example, an arrangement for turning variableangle nozzle guide vanes of a turbine is now described with reference to the accompanying drawing which is a view in the direction of the axis of rotation of the turbine.

In the drawing, reference 1 denotes the axis of rotation of the turbine. An annular rack for turning the nozzle guide vanes through individual pinions is indicated by reference 2. One pinion and the associated nozzle guide vane are shown and are indicated by references 10 and 11 respectively. The pinion 10 is carried by a shaft 12 extending longitudinally from the vane 11 and rotation of the pinion 10 by the rack 2 effects rotation of the guide vane. Circumferential movement of the rack 2 effects similar movement of all the vanes 11 simultaneously. In accordance with the invention, the annular rack has secured to its outer periphery a mounting block 3 in which is secured one end of a leaf spring 4. The leaf spring 4 extends substantially tangentially of the annular rack, but can flex towards or away from the peripheral surface of the annular rack. The end of the leaf spring 4 remote from the mounting block 3 is secured to a link 5, which is pivotally attached to the radially outer end of an arm 6 of a bellcrank lever. The bellcrank lever has a second arm 7 to which a fluidoperated plunger 8 is pivotally attached. Reciprocation of the plunger 8 effects angular oscillation of the bellcrank lever between the position shown in full lines and the position indicated by chain line. This in turn moves the link 5 which pulls or pushes the leaf spring 4 and hence turns the annular rack 2 which turns the pinions 10 and hence the nozzle uide vanes i1. The leaf spring 4 flexes as necessary so as to fo ow a smooth curve between the link 5 and the mounting block 3.

I claim:

1. A turbine having a ring of variable-angle nozzle guide vanes, each arranged to be turned simultaneously about an axis extending longitudinally thereof, a driving pinion coaxial with each vane and an annular rack coaxial with the turbine and engaging said driving pinions, wherein the improvement comprises a substantially tangentially extending leaf spring secured at one thereof to said annular rack and a lever secured to the other end of said leaf spring and by which the annular rack is to be angularly turned to effect simultaneous turning of said pinions and hence of the nozzle guide vanes, said leaf spring being flexible in a direction toward and away from the circumference of said annular rack.

2. A turbine as claimed in claim 1 including a link secured at one end thereof to the end of said leaf spring remote from said annular rack and pivotally connected at the end thereof remote from said leaf spring to the lever.

3. A turbine as claimed in claim 2 including a bellcrank having one arm forming said lever and another arm to which an operating force is to be applied, the turbine also including an operating device connected to said other arm of the bellcrank.

4. A turbine as claimed in claim 3 in which said operating device is a fluid-operated plunger. 

2. A turbine as claimed in claim 1 including a link secured at one end thereof to the end of said leaf spring remote from said annular rack and pivotally connected at the end thereof remote from said leaf spring to the lever.
 3. A turbine as claimed in claim 2 including a bellcrank having one arm forming said lever and another arm to which an operating force is to be applied, the turbine also including an operating device connected to said other arm of the bellcrank.
 4. A turbine as claimed in claim 3 in which said operating device is a fluid-operated plunger. 